Productus. MOLLUSCA. SESSILIA. 379 



7. P. Martini Semicylindrical, convex above, with a flattened front, 



deeply striated ; a few spines ; lesser valve nearly flat, deeply inserted ; hinge 

 line equal to the width of the shell — Ammonites prod. Mart. Derb. t. xxii. 

 f. 1, 2, 3. P. Martini, Sower. Min. Conch, t. cccxvii. f. 2, 3, 4 ; and P. concin- 

 nus lb. t. cccxviii. f. i.— In Carboniferous Limestone, common. 



8. P. lobatus Convex valve with a mesial groove ; spines few ; the ribs 



coarser, and the sides more compressed than the preceding species, with which 

 it may be readily confounded.— Sower. Min. Conch, t. cccxviii. f. 2-6 ; and 

 P. sulcatus, lb. t. cccxix. f. 2 — In Carboniferous Limestone. 



9. P. horridus Quadrangular, with a large furrow along the middle, ear- 



ed, thorny ; ears prominent, subcylindrical ; beak much incurved, large— 

 Sower Min. Conch, t. cccxix. f. 1 — In Magnesian Limestone. 



10. P. humerosus.— Oblong, squarish, depressed, striated, spinose ? or his- 

 pid ? hinge line less than the width of the valve ; in the larger valve are two 

 very deep cavities near the beak, and a third connected with the beak ; front 

 flattish Sower. Min. Conch, t. cccxxii — In Magnesian Limestone. 



11. P. giganteus Transversely oblong, with dilated sides and rugose irre- 

 gular strue, longitudinally undulated or sulcated ; larger valve gibbose.— 

 Amonites giganteus, Mart. Derb. t. xv. P. gig. Sower. Min. Conch, t. cccxx. 

 — Carboniferous Limestone. 



12. P. crassus.— Hounded, longitudinally sulcated, ard striated ; striae tu- 

 bercular ; sides not dilated. — Ammonites crassus, Mart. Derb. t. xvi — Car- 

 boniferous Limestone. 



13. P. personatus.— Hemispherical, irregularly striated, beneath very con- 

 cave ; within the larger valve are three deep cavities, one connected with 



the beak, and two remote Sower. Min. Conch, t. cccxxi. — Carboniferous 



Limestone. 



14. P. punctatus Shell rounded, slightly elongated, with a shallow mesial 



depression transversely sulcated ; the anterior part of the furrows and the 

 ridges thickly covered with long cylindrical spines, concealing the shell — 

 Concbse pilosse, Ure, Ruth. 316. t. xv. f. 7- Anomites punctatus, Mart. 

 Derb. t. xxxvii. f. 6, 7, 8. P. punct. Sower. Min. Conch, t. cccxxiii — In Car- 

 boniferous Limestone. 



15. V.fimbriatus. Shell slightly elongated, rounded, gibbous towards the 



apex, with rather distant transverse ridges ; thinly spinous — Sower. Min. 

 Conch, t. cccclix. f. 1. — Carboniferous Limestone. 



16. P. semireticulatus.— Semiorbicular,_with a shallow mesial depression ; 

 longitudinally striated, the striae rude, "strong, and unequal; transversely 



wrinkled Anomites semi. Mart. Derb. t. xxxii. f. 1-4 — In Carboniferous 



Limestone. 



17. P. hemispheericus Hemispherical, longitudinally striated ; striae fine ; 



lower valve very concave Sower. Min. Conch, t. cccxxviii — Carboniferous 



Limestone. 



18. P. comoides Semicircular, gibbose, very finely striated; disk inflated; 



back straight, extending the whole width of the shell — Sower. Min. Conch, 

 t. cccxxx. — Carboniferous Limestone. 



19. P. latissimus.—Transverely oblong, depressed, coarsely striated ; beak 

 much incurved; hinge line very long.— .Sower. Min. Conch, t. cccxxx.— Car- 

 boniferous Limestone. 



